A tilt angle sensor is a device for measuring a relative angle between a measured object and a horizontal plane, and is commonly used for monitoring and measuring tilt angles of bridges, mines, roads, dams, and the like. The tilt angle sensor is used generally for operation in open air environments, and thus the tilt angle sensor is required to have high reliability and stability. At present, the commonly used tilt angle sensors have various types of structures, such as a bubble type, a differential transformer type, a capacitance type, a potentiometer type, a magneto-sensitive type, and a polarizing plate type, etc.